They're discussing the effects of "copyleft" on closed-source developers, but like every other discussion of this I've seen, they fail to mention that the GPL unnecessarily applies also to other open-source developers.

There is no good reason I've heard why the GPL (version 3, at least) shouldn't make an exception for other open source to at least allow a GPL'd property like the "readline" library, to be linked into programs with non-GPL open source software like something BSD-licensed, without requiring "the whole" to be licensed under terms like the GPL's.

Now, I know that some (maybe RMS) say there's no problem putting the whole under GPL, even if parts are BSDL'd, but others, like me, disagree, and that inhibits the progress of open source development.